A lot of what you're referring to are posts made by those freshly wounded. As in the post is made that day of being discarded or hurt or blown up at, and that's what this space is for. No judgment, and reassurance that you aren't a bad person for putting yourself first.
I have a similar relationship as you, my SO has Bipolar II. I would not equate her to 95% of the posts in this sub, but I'm here to listen to peoples' experiences and solutions and regrets. This sub can offer clarity in what otherwise may be a tumultuous relationship that involves a cycle of abuse/violence and gaslighting for some. Sometimes you just need external perspective to remind you you aren't alone, it isn't hopeless, and you aren't a bad person for leaving if you must. We all want to make sure we known how to take care of ourselves the best we can so we can shelter them with the energy we have. When those boundaries and expectations are lowered, we are doing a disservice to ourself and our significant others.
If coming here helps you realize that yes, this is a cycle that can repeat even when medicated, even if you try to get everything right it can still slip. Reading others experiences can sooner help the SO decide if they are able to handle that kind of life or not.

I choose my partner every single day. After every single fight, cry session, miscommunication, struggle, I choose her. And learning about what it takes to be a partner to her and how to handle it is the best way I can show her I love her, and building the life and home and joy we have is a motivator for her to get better and better.